THE SECONDARY STRATA. 259 



sestuary, as may he done respecting similar cases in the 

 old red sandstone, an unquestionable produce of de- 

 gradation and transportation. And though it should 

 really contain shells in any place, these may he the 

 remains of an organic creation, perhaps yet scanty, 

 whether a renovated one or not, under those circum- 

 stances of revolution which depressed the coal strata. 

 It is often oolithic, and further, sandy ; facts equally 

 marking its origin in degradation, and consequently, 

 as a limestone, from former limestones ; while if its 

 progenitor contained shells and corals, as we know that 

 it did, we might account for even its traces of shells, 

 or entrochi, or whatever else, without the aid of living 

 animals, assisting to form it hy their own disinte- 

 gration. 



Considering therefore these circumstances, and con- 

 joining with them the revolution depressing the coal 

 strata, additional proofs of which are found in its con- 

 glomerate structure, and in those conglomerates con- 

 sisting of the mountain limestone, the solution of its 

 origin seems to me this, namely, that it was formed, 

 principally, if not entirely, from the waste of the 

 mountain limestone, remaining partially ahove the 

 surface after the depression of the coal strata ; while 

 some portions have been deposited on this series, and 

 others in a lateral order, under the necessity formerly 

 explained, and while it should not be the produce of liv- 

 ing shells, because a living creation should have suf- 

 fered in the preceding revolution, just as it did in that 

 which preceded the deposition of the old red sand- 

 stone. 



If this be the explanation, even the magnesia which 

 it contains may be used as an argument, since it occurs 

 also in the mountain limestone ; and if it be not re- 

 ceived as such, I have but one more suggestion to offer. 



S 2 



